Energy Expenditure at Rest and during Walking in Patients with Chronic Respiratory Failure: A Prospective Two-Phase Case-Control Study

BACKGROUND Measurements of Energy Expenditure (EE) at rest (REE) and during physical activities are increasing in interest in chronic patients. In this study we aimed at evaluating the validity/reliability of the SenseWear®Armband (SWA) device in terms of REE and EE during assisted walking in Chronic Respiratory Failure (CRF) patients receiving long-term oxygen therapy (LTOT). METHODOLOGY/PRINCIPAL FINDINGS In a two-phase prospective protocol we studied 40 severe patients and 35 age-matched healthy controls. In phase-1 we determined the validity and repeatability of REE measured by SWA (REEa) in comparison with standard calorimetry (REEc). In phase-2 we then assessed EE and Metabolic Equivalents-METs by SWA during the 6-minute walking test while breathing oxygen in both assisted (Aid) or unassisted (No-Aid) modalities. When compared with REEc, REEa was slightly lower in patients (1351±169 vs 1413±194 kcal/day respectively, p<0.05), and less repeatable than in healthy controls (0.14 and 0.43 coefficient respectively). COPD patients with CRF patients reported a significant gain with Aid as compared with No-Aid modality in terms of meters walked, perceived symptoms and EE. CONCLUSIONS/SIGNIFICANCE SWA provides a feasible and valid method to assess the energy expenditure in CRF patients on LTOT, and it shows that aided walking results in a substantial energy saving in this population.